1. Field of the Invention
The invention relates to processes of preparing instant wheat cereals. The invention also relates to instant or ready-to-eat wheat cereals.
2. Prior Art
Ready-to-eat cereals are available in a variety of forms and are normally consumed with milk and sometimes sugar. Flaked varieties are very popular. During processing the starch is gelatinized, halting enzymic reactions and thus providing product stability and good shelf life.
Matz, Samuel A., "Cereal Technology", The Avi Publishing Company, Inc., (1970), pages 229 to 231, teaches a process for the manufacture of cold-eating wheat flakes from kernels of wheat. After cleaning and classifying according to size, the wheat is tempered with added moisture in steel bins of small diameter at approximately 80.degree. F. for 24 hrs. The wheat can be transferred one or more times during this period if such a procedure is necessary in order to keep the temperature within reasonable limits. After tempering, the wheat is steamed at atmospheric pressure until it reaches about 203.degree. F. and 21 percent moisture. The steamed wheat is "bumped" between smooth steel rollers set considerably farther apart than are flaking rolls. Such treatment flattens the grain slightly and ruptures the bran coat in several places making the kernel more permeable to the moisture added during the cooking step. The flattened kernels are transferred to the pressure cookers, which are similar to those used for corn flakes, and the other ingredients are added. Such other ingredients include sugars, salt, malt, and sometimes a coloring substance such as caramel.
The Matz process continues with the retort contents being cooked at 20 psi steam pressure for 90 minutes while the vessel rotates slowly. After cooking, the grains are soft, translucent and brown and they contain about 45 to 50 percent moisture. The starch has, of course, been completely gelatinized. Rotation of the opened retort dumps the contents onto a moving belt which transfers the cooked mass to a chute leading to a "Wiggler." The Wiggler consists of a horizontal perforated disc, through which warm air is blown in an upward direction, and a rotating arm carrying vertically-oriented inflexible fingers around its upper surface. The clumps of slightly adherent grain are dropped onto the center of the perforated disc and are broken up and the individual grains moved to the outer edge of the disc by the moving fingers. The individual grains fall from the edge of the disc and are transferred pneumatically to a horizontal rotating cylinder fitted with internal louvers. In this drier, air at 250.degree. to 300.degree. F. is passed over the grain, reducing it to 28 to 31 percent moisture. Holding bins are used to store the material until it can be transferred to the presses. At this point, the grains are still intact and are rather tough and chewy in texture. Subsequent processing is designed to secure the required crispness. First, the wheat pieces travel through a drier. This can be a Proctor and Schwarz drier composed of 3 sections, the first at 280.degree. F., the second at 290.degree. F. and the third unheated. Rate of movement of the material is adjusted to yield a product containing about 21 percent moisture. A spray of B-complex vitamins is applied at this stage.
Screw conveyors or drag chain conveyors, in the Matz process, transport the partially dried pellets to the flaking rolls. Just before falling into the flaking rolls, the pellets are heated to about 180.degree. to 190.degree. F. and they become plasticized. The large steel flaking rolls are practically identical with those used for making corn flakes. The pressure applied to the pellets increases their diameter several times and decreases their thickness proportionately. When they leave the rolls, the flakes contain 10 to 15 percent moisture and are still slightly flexible. To obtain the desired crispness, they are toasted and dehydrated to less than 3 percent moisture content in a drier with a perforated travelling metal belt. Temperature in the oven may be divided into 4 regions; for example, heated sections at 310.degree., 300.degree. and 280.degree. F., and an unheated section to partially cool the product. The decreasing temperature is said to promote the development of the desirable curling and blistering.
Matz, Samuel A., ibid., pages 226 to 229, teaches a method of producing corn flakes. Corn is milled to produce large pieces free of germ and bran. The corn grits are placed in a cylindrical pressure cooker along with flavoring syrup consisting of sugar, malt (nondiastatic), salt and water. During the cooking period the charge accumulates additional water from the steam introduced into the retort, rising to about 33 percent moisture. Cooking is done in the slowly rotating retort at 15 to 23 psi steam pressure for 1 to 2 hours. After cooking, the pressure is reduced to the atmospheric level, the retort is opened and the contents are dumped out onto a moving belt. After the lumps from the cooker are broken down to individual particles by a revolving reel, they are dried. The dried particles contain 19 to 23 percent moisture, but this water is unevenly distributed, so the material is transferred to tempering bins for several hours (as many as 24) so that the moisture can equilibrate. After tempering, the hard, dark brown grits are ready for flaking. The flaking rolls are steel cylinders cooled by internal circulation of water. The cooked dried grits are pressed into thin flakes as they pass through the rolls. The product is still rather flexible at this time, lacking the desired crispness and the preferred flavor of the finished corn flake. From the rolls, the flakes pass directly to the rotating toasting ovens, which are usually gas fired. In addition to being thoroughly dehydrated by the process, the flakes are toasted and blistered. They emerge from the oven with less than 3 percent moisture. The corn flakes are then cooled in expansion bins.